a) Field of the Invention
The present invention relates to a modifying agent (or modifier) for improving various properties of porous stonework materials such as concrete products like concrete panels, light-weight fire-resistant building materials, etc., other cement products, calcium silicate boards, gypsum products, and so forth; and those porous materials such as woven fabrics, paper, ligneous materials, and others, by rendering them non-porous. With such modifier being used, the above-mentioned porous stonework materials improve their water-resistant property, dust-preventing property, wear-resistant property, mechanical strength, and other properties, while those porous materials like woven fabrics, paper, ligneous materials, etc. are imparted various characteristics such as fire-resistant property, prevention of contraction due to drying, and others.
The present invention is also concerned with a method of modifying porous materials by use of such modifier, and the above-mentioned porous materials as modified by such method.
b) Description of the Background
The tactile surface of a stonework material is primarily porous, and represents, when viewed in an enlarged scale, surface conditions similar to sponge, which has water-absorbing property. On account of this, water content penetrates unceasingly into the body of the material through small pores within it, along with which other foreign substances such as dust, fine particles, oily substances, acids, etc. also pass through. This brings about corrosion of the stonework material. Moreover, the penetrated water goes through cycles of freezing/defrosting due to differences in atmospheric temperature. As a consequence of which, the stonework material tends to readily bring about peeling and falling, swelling, groove-forming, breaking, etc., under the stress induced by expansion and contraction.
In particular, concrete or the like materials readily generate dust particles due to its being worn-down at the place where it is used. Further, a road bed, a pedestrian zone, a car park, etc. are required to improve their wear-resistance, water-proof (water tightness), dust-preventive property, mechanical property. etc.. If oily contaminants such as oil, grease. etc. stick onto the surface of the stonework material, these contaminants penetrate into the material through small pores within it, and become unable to be removed by wiping with use of a wet mop, etc..
The stonework material, for example marble to name one, has so far been used as an outer covering. Even in that case, however, there takes place corrosion due to its water-absorbing property as mentioned above, or moss grows due to absorption of organic substances, whereby the outer appearance of the stonework structures become spoiled in most occasions.
In order to avoid such undesirable phenomenon, there has so far been attempted various preventive methods such as one in which the surface of the stonework material is covered with a resin; or another in which the small pores in the stonework material are filled with an inorganic type materials or an organic type material; as well as others.
Furthermore, as the fire-retarding treatment for paper, fibers, ligneous material, etc., there has so far been practiced an impregnation treatment with use of a chemical prepared from combination of boric acid and borax or Glauber's salt, etc..
However, the abovementioned method of covering the surface of the stonework material not only spoils the sense of touch on the original surface of the material, but also brings about impairment in the outer appearance due to deterioration of the material surface by the swelling of the coated resin with water content therein, absorption of oxygen and ultra-violet rays with the consequence that the stonework material becomes inappropriate as an outer covering material.
There have been made publicly known a large number of inorganic type and organic type pore-filling agents. Examples of the inorganic type pore-filling agent are: water-soluble silicate compounds such as sodium silicate, etc., a solution of which is applied to, and impregnated in, the surface of the stonework material for its reinforcement; a synthetic resin emulsion prepared by mixing very fine powder of non-crystal siliceous material such as sheet glass or glass chips, etc., and a cementitious material, which emulsion is injected into the stonework materia to penetrate therewithin (as disclosed, in laid-open Japanese patent application No. 3-164458); and others. On the other hand, examples of the organic type pore-filling gent are polyurethane resin, epoxy resin, and other organic polymeric materials, which are filled in the voids of the stonework material in various ways.
The conventional methods of charging the pore-filling agent are all to impregnate it from the surface of the stonework material, which method is, however, unable to avoid the pressure of small air bubbles confined in the small pores of the stonework material, hence it is difficult to render the material perfectly non-porous. On account of this, it is not possible to prevent the pore-filling agent from its elution and deterioration over a long period of time due to insufficient water-resistant property after its curing.
On the other hand, those porous materials such as paper, fibers, ligneous materials, etc. which have been modified by the conventional method of subjecting them to immersion into a chemical prepared by combining boric acid and borax or Glauber's salt, etc. are unable to avoid toxicity of the chemical to be eluted from the material, and shrinkage of the ligneous material due to its drying, and others.